AOTaddExtendedDataType(): Unsupported type specified. Error

Hi,I create EDT with x++,with below code

//create EDT

treenode=TreeNode::findNode(#ExtendedDataTypesPath);
try
{
treenode.AOTaddExtendedDataType(this.Kodu+ “EDT_AGC”,typeof(this.EDT_Tipi));
}
catch
{}
treenode=null;

//set extend type

treenode=TreeNode::findNode(#ExtendedDataTypesPath).AOTfindChild(this.Kodu+ “EDT_AGC”);
Props = treenode.AOTgetProperties(false,false);
Props = Global::setProperty(Props,‘Extends’,this.EDT_Tipi);
treenode.AOTsetProperties(props);
treenode.AOTsave();
treenode=null;

But I take AOTaddExtendedDataType(): Unsupported type specified. error,How can I solve this,please help me

Thanks